Fit matters. Suit and sport coat sizes have one number and one letter (for example, 38S, 40R, 42L). The number is your chest measurement and the letter refers to the jacket's length ’ short, regular ...
When measuring suit sizes, the 42L size denotes a suit jacket tailored for individuals with a chest measurement of 40-42 inches, a waist size of 34 or 36 inches, and a height of 5'11.5"-6'2.5".